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Troubleshoot proxy filtering Options
Christian Porzio
Posted: Wednesday, April 26, 2017 11:17:03 AM
Rank: Advanced Member
Groups: Member

Joined: 10/4/2016
Posts: 104
Hi,

We are experiencing some proxy access issues when using EO.Web at a number of client sites.

The proxy is implemented using a PAC file that looks like this:

Code: JavaScript
var proxy = "PROXY PROXY1:9000; PROXY PROXY2:9093; // more IPs:Ports....";

// Default localhost for denied connections
var deny = "PROXY 127.0.0.1:65535";

// Bypass the proxy server and try to connect directly via local network
var bypass = "DIRECT";

function FindProxyForURL(url, host)
{
//
//By default, all aa.com child domains are trusted.  Only list third-party domains which are not part of aa.com.
//
 alert('checking host='+host);
     if	(
		   shExpMatch(host, "*.aa.com*")
		|| shExpMatch(host, "*entrust.net*") // added for access thru Firefox
// more authorized domains...
    	)
		
	 // If the host is defined return the proxy list, else bypass the proxy and try to connect via local network. 
	 return proxy;
  	 else 
	{
		alert('bypass host='+host);
		return bypass;
	}
}


When we used IE we could access our sites, but any other browser failed.

We were able to troubleshoot the issue with Firefox because all the alert(...) calls were reported in the web console of the browser. And we found out that we needed to add *entrust.net* in the white list. That was enough for Firefox to access all our sites.

However we were not able to resolve the problem with EO.Web engine. I tried to add in the native options log settings: --log-level=0 --log-net-log=c:\temp\MyNetLog.txt but that did not produce any log and the web console did not report any log eiter - unlike with Firefox.

I am not sure at this point if it is a EO.Web issue or a Chrome one. Unfortunately the client machines I had access did not allow to install Chrome native for me to make that distinction.

I suspect this is a Chrome issue anyway because I read some forums mentioning its proxy implementation may differ from IE.

In any cases, I would be very grateful if you had any advice on how to troubleshoot this proxy access. I just need to log what sites are being inspected by our pac script and which ones are rejected and falling in the bypass category.

I also tried to invoke window.console(...) in place of alert but that was breaking the pac scripting.

For now we serve our sites using Firefox, needless to say this has to be a temporary work around as we need to run our EO.Web wrapper at those client sites.

As always, thank you very much for your input on this matter.
eo_support
Posted: Wednesday, April 26, 2017 12:21:28 PM
Rank: Administration
Groups: Administration

Joined: 5/27/2007
Posts: 24,067
Hi,

We are not terribly familiar with this part either. As far as I know the only thing we do about proxy is to bypass all the built-in proxy resolving logic when you set EngineOption.Proxy property. If you do not set that properly, then the default logic kicks in, including the PAC logic.

Your best option would be try to install Google Chrome and use that to troubleshoot this issue. For Chrome, alert in a PAC file will go to Chrome's net-log. There are several ways to capture net-log but we do not support any. --log-net-log is the correct command line argument for Chrome. You can also type in chrome://net-internals to view/capture net-logs.

Thanks!
Christian Porzio
Posted: Wednesday, April 26, 2017 4:51:46 PM
Rank: Advanced Member
Groups: Member

Joined: 10/4/2016
Posts: 104
Thank you for your quick reply. Unfortunately installing Chrome on these workstations might not be an option because they are located in a secure area and this will require several levels of approval.

Also setting the EngineOption.Proxy is not practical because the location of the pac file is different for each site and it is not realistic to manage a different configuration for each site. Hence we are left to use default logic.

Just to make sure I understand it right, at the moment: Is there an option in EO.Web to would allow tracing alerts from the pac script?

If NO, then do you have any plan to include this feature anytime soon in your wrapper?

Thanks again & Kind Regards
eo_support
Posted: Wednesday, April 26, 2017 5:19:49 PM
Rank: Administration
Groups: Administration

Joined: 5/27/2007
Posts: 24,067
No. We are not aware of any option for EO.WebBrowser to trace alerts in pac script and at this moment we do not have any plan to add it. This is because it requires quite some code changes and the issue can usually be resolved by installing Chrome browser, which for most cases is not an issue (I understand it is indeed an issue in your case).

For stability purpose, generally if an issue can be resolved/troubleshot using Google Chrome, you will need to use Google Chrome. This is because it is not practical for us to add every piece that is in Google Chrome but not in EO.WebBrowser back to EO.WebBrowser ---- if we were to do that then you would essentially end up with a copy of Google Chrome itself. So there are cases we won't investigate or won't support. Exactly what to support or not depends on how much it would cost on our end (both in term of immediate development cost and in term of possible impact on long term maintenance/stability) versus how much our customers can benefit from it. In your case, we believe it's a more viable option for you to either pursue approval of installing Google Chrome browser, or setting up a staging/test system in order to troubleshoot than making changes on our product.


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